Improve tool usage with source generators

[awaescher]

This pull request introduces a source generator that can generate Ollama tools from simple method implementations. Usage can be found in the ToolConsole demo:

/// <summary>
/// Gets the current weather for a given location.
/// </summary>
/// <param name="location">The location or city to get the weather for</param>
/// <param name="unit">The unit to measure the temperature in</param>
/// <returns>The weather for the given location</returns>
[OllamaTool]
public static string GetWeather(string location, Unit unit) => $"It's cold at only 6° {unit} in {location}.";

• use object[] as tools instead of Tool[] in web requests to prevent dependencies
  see Metadata and return description for the tools #143
• introduce a source generator that generates the code for tools (meta data and implementation)
  • allow static tool implementation as shown above for demos and simple calculations
  • allow non-static tool implementations with arguments and injected services
  • allow definition of tool meta data only (maybe with interfaces?)
  • make arguments required unless they are optional
  • automatic execution of requested tools by the tool calls provided by the LLM
  • backpropagation of the tool results (as message with role "Tool") to the LLM
  • use code enums for available values like "enum": ["celsius", "fahrenheit"] (see Unit in the code above)
    • error handling for enum values from the LLM that cannot get parsed
  • parse meta data such as method and parameter names from XML summaries like in the code above
    • C#
    • F#?
    • Visual Basic?
  • build a separate NuGet package for the source generator